feat: редактирование фото через xAI Grok Imagine API (/v1/images/edits) вместо Codex CLI

EDIT_ENGINE=grok по умолчанию, XAI_API_KEY/XAI_BASE_URL/XAI_IMAGE_MODEL/XAI_TIMEOUT_MS;
Codex остаётся для подсказок и как fallback (EDIT_ENGINE=codex).

test/grok-edit.test.js

@@ -0,0 +1,60 @@
+"use strict";
+
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { XaiImageClient } = require("../src/core/xai/client");
+const { buildGrokEditPrompt } = require("../src/core/engines/grok-edit-engine");
+const { loadConfig } = require("../src/config");
+
+describe("xAI Grok image edit", () => {
+  test("sends JSON to /images/edits and decodes b64_json", async () => {
+    let captured;
+    const fetchImpl = async (url, opts) => {
+      captured = { url, opts, body: JSON.parse(opts.body) };
+      return new Response(JSON.stringify({ data: [{ b64_json: Buffer.from("JPEGDATA").toString("base64"), mime_type: "image/jpeg" }] }), { status: 200 });
+    };
+    const c = new XaiImageClient({ apiKey: "k", baseUrl: "https://api.x.ai/v1/", fetchImpl });
+    const r = await c.edit({ prompt: "p", images: [{ buffer: Buffer.from("a"), mimetype: "image/png" }] });
+    assert.equal(captured.url, "https://api.x.ai/v1/images/edits");
+    assert.equal(captured.opts.headers.Authorization, "Bearer k");
+    assert.equal(captured.body.model, "grok-imagine-image-2.0");
+    assert.equal(captured.body.response_format, "b64_json");
+    assert.equal(captured.body.image.type, "image_url");
+    assert.ok(captured.body.image.url.startsWith("data:image/png;base64,"));
+    assert.equal(r.buffer.toString(), "JPEGDATA");
+  });
+
+  test("uses images[] for multiple inputs and surfaces API errors", async () => {
+    let body;
+    const fetchImpl = async (_u, o) => {
+      body = JSON.parse(o.body);
+      return new Response(JSON.stringify({ error: "bad" }), { status: 400 });
+    };
+    const c = new XaiImageClient({ apiKey: "k", fetchImpl });
+    const img = { buffer: Buffer.from("a"), mimetype: "image/jpeg" };
+    await assert.rejects(c.edit({ prompt: "p", images: [img, img] }), /Grok API 400: bad/);
+    assert.equal(body.images.length, 2);
+    assert.equal(body.image, undefined);
+  });
+
+  test("fails clearly without API key", async () => {
+    const c = new XaiImageClient({ apiKey: "" });
+    await assert.rejects(c.edit({ prompt: "p", images: [{ buffer: Buffer.from("a") }] }), /XAI_API_KEY/);
+  });
+
+  test("prompt mentions reference region", () => {
+    const t = buildGrokEditPrompt({ prompt: "add hat", hasReference: true, region: { x: 1, y: 2, w: 3, h: 4 } });
+    assert.match(t, /add hat/);
+    assert.match(t, /x=1, y=2, width=3, height=4/);
+  });
+
+  test("config defaults and key is not in sanitized output", () => {
+    const cfg = loadConfig({ XAI_API_KEY: "secret" });
+    assert.equal(cfg.EDIT_ENGINE, "grok");
+    assert.equal(cfg.XAI_IMAGE_MODEL, "grok-imagine-image-2.0");
+    const s = cfg.getSanitized();
+    assert.equal(s.XAI_API_KEY, undefined);
+    assert.equal(s.XAI_API_KEY_SET, true);
+    assert.throws(() => loadConfig({ EDIT_ENGINE: "foo" }));
+  });
+});